1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing the same and, more particularly, to a semiconductor device that has an interlayer insulating film for covering a copper wiring and having a low dielectric constant and a method of manufacturing the same.
2. Description of the Related Art
In recent years, with the progress of higher integration density in the semiconductor integrated circuit device, the increase of the data transfer rate is requested. Therefore, the insulating films having low dielectric constant and hence the small RC delay (referred to as a xe2x80x9clow dielectric constant insulating filmxe2x80x9d hereinafter) is employed. Among these films are the SiOF film (relative dielectric constant of 3.5 to 3.8), the porous SiO2 film (relative dielectric constant of 3.0 to 3.1), etc.
On the other hand, the wiring material is being changed from the conventional aluminum (Al) to the copper (Cu) of the low electric resistance.
In order to fabricate the semiconductor device having the conventional multi-layered copper wiring, the low dielectric constant insulating film is formed on the copper wiring as the interlayer insulating film. However, in general the copper in the copper wiring is ready to diffuse into the low dielectric constant insulating film, which increases the leakage current between upper and lower wirings. Therefore, in order to prevent the diffusion of the copper element into the low dielectric constant insulating film, the barrier insulating film formed of a silicon nitride film or the SiC-based barrier insulating film is simultaneously being developed.
Thus, in the semiconductor device having the copper wiring, the barrier insulating film formed of the silicon nitride film or the SiC-based barrier insulating film and the low dielectric constant insulating film are laminated in sequence on the copper wiring.
However, while the barrier insulating film formed of silicon nitride film is dense, its relative dielectric constant is high such as about 7. In contrast, the SiC-based barrier insulating film has the relatively low relative dielectric constant such as about 5, but it contains a large quantity of carbon and thus the increase of the leakage current cannot be sufficiently suppressed.
It is an object of the present invention to provide a semiconductor device capable of reducing the leakage current between the copper wirings that sandwich the interlayer insulating film of multi-layered structure, together with maintaining the low dielectric constant of the interlayer insulating film, and a method of manufacturing the same.
In the present invention, an insulating film for covering a copper wiring is formed by plasmanizing and reacting a film forming gas containing at least an alkyl compound having siloxane bonds and any one of nitrogen (N2) and ammonia (NH3).
The insulating film may also be formed by plasmanizing and reacting a film forming gas containing at least methylsilane (any one of monomethylsilane (SiH3(CH3)), dimethylsilane (SiH2(CH3)2) trimethylsilane (SiH(CH3)3), and tetramethylsilane (Si(CH3)4)), an oxygen-containing gas (any one of N2O, H2O and CO2), and any one of nitrogen (N2) and ammonia (NH3).
Since the film forming gas contains any one of nitrogen (N2) and ammonia (NH3), the formed film contains nitrogen in any method of the present invention. Therefore, the insulating film that has the density close to the silicon nitride film and has the lower dielectric constant than the silicon nitride film can be formed.
Particularly, when a parallel-plate plasma film forming equipment is employed, connecting a low frequency power and applying the low frequency to an electrode, that holds a substrate, can make the low dielectric constant insulating film denser.
Furthermore, when the interlayer insulating film has multi-layered structure, it is preferable to form a barrier insulating film, which constitutes one of the film of the multi-layered structure and is in contact with a copper wiring, in accordance with the above method since this prevents copper in the wiring from diffusing into the interlayer insulating film and hence a leakage current between the copper wirings can be reduced. In this case, the dielectric constant of the overall interlayer insulating film can be lowered using an insulating film, which has lower dielectric constant than that of the barrier insulating film, for a film that constitutes other film of the multi-layered interlayer insulating film.
As described above, according to the present invention, the interlayer insulating film having low dielectric constant together with reducing the leakage current between the copper wirings that sandwiches the same can be formed.